Adding any emoji as a reaction remains under review.
I am marking this as partially done to let you know a new reactions bar with Like, Heart, Laugh, Surprised, Sad, and Angry has begun rolling out to all users.
😥 I wanted pizzas and beers and bears and ducks and rockets and cars and flags not just those 5
I switched from Slack to Teams and this is the feature that makes me want Slack back
This item is still on the backlog.